The present invention generally relates to intravascular catheters. More specifically, the present invention relates to intravascular coronary guide catheters.
Intravascular guide catheters are commonly used to guide therapeutic and diagnostic devices to remote locations in a patient""s vascular system. For example, coronary guide catheters are commonly used to position a balloon catheter in a patient""s coronary artery to perform a percutaneous transluminal coronary angioplasty (PTCA) procedure. An example of a conventional PTCA guide catheter 10 is illustrated in FIG. 1. The PTCA guide catheter 10 includes an elongate shaft 12 having a proximal end, a distal end and a lumen extending therethrough. A hub 14 is connected to the proximal end of the elongate shaft 12. The distal end of the elongate shaft 12 includes a preformed curved portion 16 and a distal tip portion 18, the geometry of which may vary depending on the particular vascular anatomy being navigated.
In a typical PTCA procedure, the distal end of the guide catheter 10 is inserted into the patient""s femoral artery near the groin, and is advanced up the descending aorta 20, across the aortic arch 22, and down the ascending aorta 28 until the distal tip 18 is seated in the ostium of the right coronary artery (RCA) 24 or the left coronary artery (LCA) 26 as illustrated in FIG. 2. Usually, approximately 1 mm-5 mm of the distal tip 18 is seated in the ostium. Once the distal tip 18 is seated in the ostium, a therapeutic or diagnostic device (e.g., a balloon catheter, an atherectomy catheter, an IVUS catheter, etc.) may be inserted into the lumen of the guide catheter 10, advanced therethrough, and navigated through the lumen of the coronary artery 24/26.
Because the lumen of the coronary artery 24/26 is often restricted or tortuous, it is often difficult to navigate intravascular devices therethrough, particularly when accessing distal vascular sites. When resistance to advancement through the lumen of the coronary artery 24/26 is encountered, the physician typically applies additional pushing force to the intravascular device in an attempt to overcome the resistance. If significant resistance is encountered, the distal tip 18 of the guide catheter 10 tends to back-out of the ostium. When the distal tip 18 backs-out of the ostium, it is difficult if not impossible to advance the intravascular device any further and it is likely that the intravascular catheter will prolapse in the lumen of the ascending aorta 28.
To address this problem, some physicians attempt to deep-seat the distal tip 18 in the ostium. However, this deep-seating technique often causes misalignment between the lumen of the guide catheter 10 and the lumen of the coronary artery 24/26, thereby compromising advancement of intravascular devices therethrough. In addition, deep-seating the distal tip 18 may cause unnecessary trauma to the inside surface of the coronary artery 24/26, potentially exacerbating the underlying clinical condition being treated and/or potentially causing additional clinical problems.
As an alternative to deep-seating, various means to provide a back-up support have been proposed in the prior art. For example, U.S. Pat. No. 4,813,930 to Elliott and U.S. Pat. No. 5,098,412 to Shiu propose mechanisms which utilize a structure to brace against the wall of the ascending aorta 28 opposite the ostium of the coronary artery 24/26 being accessed. Alternatively, U.S. Pat. No. 4,832,028 to Patel and U.S. Pat. No. 5,122,125 to Deuss propose an inflatable balloon at the distal end of the guide catheter to anchor the distal tip in the ostium of the coronary artery being accessed. Although each of these prior art designs may provide back-up support to the guide catheter and thereby resist back-out from the ostium, each of the proposed embodiments involve unnecessarily complexed designs which may compromise performance and handling of the guide catheter and which most certainly will increase the manufacturing cost of the guide catheter. Accordingly, there is a substantial unmet need for a guide catheter which provides enhanced back-up support without compromising performance and without substantially increasing design complexity.
To avoid the suboptimal performance associated with deep-seating conventional guide catheters and the unnecessarily complex design of the balloon-anchor guide catheters of the prior art, the present invention provides a guide catheter that includes a specially designed distal tip to frictionally engage a coronary artery adjacent its ostium. The intravasclar catheter of the present invention, which may comprise a guide catheter or a diagnostic catheter, for example, is elegantly simple in design and does not compromise performance while providing enhanced back-up support.
In an exemplary embodiment, the present invention provides an intravascular coronary catheter, such as a guide catheter or a diagnostic catheter, including a distal tip (e.g., distal 2 cm of the shaft) that has a lateral extent or profile that is larger than the lumen of the coronary artery adjacent the ostium when the distal tip is in a relaxed state such that the distal tip frictionally engages the coronary artery. The frictional engagement with the coronary artery anchors the distal tip in the ostium and thereby provides back-up support. Preferably, the distal tip is wave-shaped in two or three dimensions. The lateral extent or profile of the distal tip may be decreased (i.e., straightened) by inserting a guide wire to facilitate insertion of the distal tip into the ostium. After the distal tip is inserted into the ostium, the guide wire may then be removed to allow the lateral extent of the distal tip to increase and thereby anchor the distal tip in the coronary artery.
After the distal tip is anchored in the ostium, a balloon catheter or other intravascular device may be inserted through the guide catheter and into the lumen of the coronary artery. If resistance to advancement through the lumen of the coronary artery is encountered, the anchored distal tip of the guide catheter provides sufficient back-up support to the balloon catheter in order to overcome the resistance to advancement. If significant resistance is encountered, it is contemplated that by applying additional pushing force to the balloon catheter, the lateral extent of the distal tip may be further increased to further engage the coronary artery and thereby provide additional back-up support.